The present invention relates to the field of beam scanning, and in particular, to the use of scan modules for scanning and/or reading dataforms such as bar codes.
Two types of scan modules which scan bar codes and detect light reflected therefrom are retroreflective and non-retroreflective scan modules. An example of a retroreflective scan module is disclosed in U.S. application Ser. No. 09/275,858, filed Mar. 24, 1999, the disclosure of which is incorporated herein by reference.
A non-retroreflective axial scan module is disclosed in U.S. Pat. No. 5,506,394, the disclosure of which is incorporated herein by reference. The scan element used in the non-retroreflective scan module in the ""394 patent is a so-called axial scanner, for example, wherein a light source, such as a laser diode, produces a beam directed along an axis and a movable scan element is disposed along the axis and receives the beam to provide a scanning light beam directed generally along the axis. This provides for a scan engine or module having a narrow width.
Retroreflective and non-retroreflective scan modules are also known wherein the scanning is not axial, but rather a beam from a laser diode is projected in a direction normal to the outgoing scanning beam prior to being applied to a movable scanning element.
The non-retroreflective scan module disclosed in the ""394 patent has a number of disadvantages, in particular, the photodetector therein is not capable of receiving light reflected from a bar code without also receiving a considerable amount of noise caused by ambient light.
One object of the present invention is to provide an improvement in an axial non-retroreflective scan module wherein optics are provided to restrict the field of view of the photodetector to the vicinity of a scan line formed by the scan element.
Like an imaging system, a non-imaging collector such as the one disclosed in U.S. Pat. No. 5,778,133 increases signal, but unlike an imaging system, it does nothing to decrease the field of view. In fact, non-imaging collectors are generally used where large fields of view are desired. They are therefore a poor choice for a single line scanner. The collection system of the present invention increases signal and reduces field of view.
Another object of the present invention is to provide a pen scanner which comprises a pen housing with a writing element at one end and a non-retroreflective scan module mounted in the pen housing to emit the scanning light beam from the other end. The pen scanner is preferably self-contained and has a power source in the pen housing which can comprise a rechargeable or replaceable battery, power management circuitry, signal processing and decoding circuitry and communications circuitry to output data from the device. The communications circuitry is preferably wireless and can use the laser light source itself, a radio frequency transmitter or a light emitting diode.
A further object of the present invention is to utilize the non-retroreflective scan-module in a keychain scanner or a pendant scanner configuration.
A still further object of the present invention is to provide a scan module of either the non-retroreflective or retroreflective type and of either the axial and non-axial type, wherein the housing thereof comprises a block mounting a light source, scan element, photodetector and optics and wherein the block is mountable on a printed circuit board having signal processing and decoding circuitry thereon to output a signal from the photodetector to the signal processing and decoding circuitry. Alternatively, the photodetector.can be mounted on the motherboard, with the block carrying the optical filter and photodiode aperture. In this case, the block carries the laser with its focusing optics, the scan motor and the collection optics (if used). It can also carry the optical filter for the. photodiode and an aperture that the photodiode receives light through. The block retains all optical components in proper alignment.
The printed circuit board may be a motherboard for another device which utilizes a scanning input. For example, the motherboard can be.a printed circuit board for a personal digital assistant, a cell phone or any other electronic device which may also require a scanning capability. In this way, the circuitry for the scan module is already provided on the circuit board and one need only mount the block with the aforesaid scanner elements thereon to scan and decode bar codes and the like.
Another object of the present invention is to provide a mounting assembly for a non-retroreflective scan module, so that it can be easily and removeably mounted in a device housing or the like.
Still another object of the present invention is to provide an improvement in an axial non-retroreflective scan module wherein the laser is pulsed at a frequency to enable the electronics to distinguish between signal and noise.
These and other objects and advantages of the present invention will be achieved in accordance with the present invention as disclosed in the following description when read in conjunction with the attached drawings, wherein: